o
DTE creates a digital signal and relays it to the Modem via an
interface via an
interface
o Modulated
signal is received
by the demodulation function
of the second
modem
o This
modem takes this
ASK, FSK, PSK
or QAM signal
and decodes it
into
whatever
format its computer can accept
o It then relays the digital signal to the
computer via an interface
o Each DCE must be compatible with both its
own DTE and the other DCE
¾ Transmission Rate
o Modems are often described as high speed
or low speed to indicate how many
bits
per second a specific device is capable of transmitting or receiving
o Limitations on the transmission rate of
the Modem
¾ Bandwidth
o Data rate of a link depends upon the type
of encoding uses and the bandwidth
of
the medium
o The
medium bandwidth is
related to the
inherent limitation of
the physical
property
of the medium
o Every line has a range of frequencies it
can pass
o If the frequency of a signal is too ow,
it cannot overcome the capacitance of
the
line
o If frequency is too high, it can be
impeded by the inductance of the line
o So every line has an upper limit and a
lower limit on frequencies of the signals
o This limited range is called Bandwidth
Telephone
Line Bandwidth
|
Tuesday, September 16, 2014
Other Interface Standards
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